1). Field of the Invention
This invention relates to a method and apparatus for testing circuits on substrates.
2). Discussion of Related Art
Electronic circuits are often manufactured on semiconductor wafers. A saw is then used to cut the wafer into individual dies, each carrying a respective circuit. The dies are then mounted to other substrates which provide both structural support and electric communication to other devices.
It is often required to test such circuits at various stages during manufacture and before they are sold. An apparatus used for testing such a circuit usually includes a plurality of spring contacts which are brought into contact with terminals connected to the circuit. Electronic signals are then relayed through the contacts and terminals between an electric tester and the circuit so as to test functional integrity of the circuit.
The invention provides a method of testing a circuit on a substrate. For example, a substrate is located in a transfer chuck, a surface of a test chuck is moved into contact with a substrate, the substrate is secured to the test chuck, the test chuck is moved relative to the transfer chuck so that the substrate moves off the transfer chuck, terminals on the substrate are moved into contact with contacts to electrically connect the circuit through the terminals and the contacts to an electric tester, signals are relayed through the terminals and the contacts between the electric tester and the circuit, the terminals are disengaged from the contacts, and the substrate is removed from the test chuck.
According to one aspect of the invention an image is recorded of a surface of the substrate while still on the transfer chuck, for example while moving off the transfer chuck.
According to another aspect of the invention, an image is recorded of a surface of the substrate in a single pass.
According to a further aspect of the invention, a plurality of substrates are simultaneously held by the test chuck and may be simultaneously scanned and may be simultaneously heated or cooled.
The invention also provides a corresponding apparatus.